Exchangeable image file format (Exif) is known as an image file format standardized by JEIDA (Japanese Electronic Industry Development Association). The Exif format is typically employed for a photograph taken by a digital camera. In the Exif format, the information added to each image file is stored in each image file as Exif information. The Exif information is used when a user selects one from a plurality of image files for printing. For example, the Exif information is date and time when the photograph was taken; type of the digital camera used for taking the photograph; aperture and shutter speed settings. The Exif information is extracted from each image file, and the pieces of extracted the Exif information is listed. The user specifies the image file to be printed on the list.
Relating the use of this additional information (Exif information), Japanese Patent Application Publication No. 2003-87701 proposes the technique of creating a circle graph based on the additional information of each extracted image file (see [0013] and [0014]). Specifically, image files are read from a memory card. The additional information of the read files (for example, name and size; and date and time of creation) is then extracted for creating a circle graph. The created circle graph indicates what percentage of the memory is consumed by each image file. The size of each image data is presented as the area of the part bordered by two radii.
In the above the technique, each image file has to be opened every time the additional information thereof is used so that the additional information is acquired from each image file. In general, the following three steps are required for reading a file: opening the file; acquiring information from the file; and then closing the file. This means that these file-opening and closing steps have to be repeated as many times as the number of the image files. As the image files increases in number, the ratio of the time required for the file-opening and closing steps increases relative to the time required for acquiring information from the image files.